Detailed studies will be made of the effects of augmenting agents and dispersing agents on the in vivo mitotic apparatus (MA) of marine eggs. The properties of isolated MAs will also be investigated and the nature of their ability to incorporate exogenous tubulin examined. Modifications of existing techniques will be made to see whether the isolated MAs can be made to function in vitro. The possible participation of actin, which appears to occur in the isolated MAs will be examined. The possibility that dinitrophenol and caffeine cause disappearance of the in vivo MA through regulation of calcium will be examined. We will follow our recent results that caffeine inhibits the appearance of glutathione reductase activity in eggs and that this ultimately has its effects through calcium by modulating a Ca ion 2 dependent ATPase. In addition, we have shown that Maytansine, a highly potent, relatively non-toxic antitumor agent, acts on MA formation in a manner similar to that of caffeine, but does not affect in vitro tubulin polymerization. We will follow this in detail since the work suggests several places where antimitotic agents may function, and we have, indeed, found several antimitotic agents not previously noted. We will also continue to examine a number of new antitumor agents isolated on this campus.